Wireless Ventilation Measurement in 3D Printed Sand Molds

Abstract

Additive Manufacturing is enabling the casting of complex geometries directly from digital design data, including 3D-scanned and reverse-engineered structures and even functionally graded lattices. By ink jetting binder into a bed of sand layer-by-layer, dimensionally precise sand molds and cores can be printed to serve as soft tooling for sand casting. However, the related increase in geometry complexity can lead to challenges in ensuring casting quality and yield. One recently explored remedy is to introduce sensors (the Internet of Things) to enable the collection of a diversity of data at difficult-to-access locations in molds in order to measure temperature, pressure, moisture, and core shift. This effort has explored measuring barometric pressure at strategic locations to evaluate the ventilation design of internal cores. Optimized and measurable ventilation can be leveraged to improve the quality of castings by reducing porosity and improving surface finish. By measuring the pressures that accumulate within cores due to binder decomposition, new ventilation designs and strategies—enabled with complex, 3D printed fluidic channels—can be explored. In this work, two castings with different metal temperatures were poured and internal pressures were measured and compared to simulations demonstrating that wireless disposable sensors can be used to measure pressure and that the measured pressure correlated with venting strategies now possible with 3D printed sand cores.